The anticoagulant and anti-inflammatory effects of recombinant human activated protein C are achieved by inhibiting which coagulation factors?

The anticoagulant and anti-inflammatory effects of recombinant human activated protein C are achieved by inhibiting which coagulation factors?

• A. Factor Va and Factor VIIIa
• B. Factor IIa and Factor Xa
• C. Factor VIIa
• D. Factor IXa

Answer: (A)

Activated protein C exerts its anticoagulant and anti-inflammatory effects mainly by proteolytically inactivating Factor Va and Factor VIIIa. These two cofactors are essential for accelerating thrombin production: Va partners with Xa to form the prothrombinase complex that converts prothrombin to thrombin, and VIIIa partners with IXa to form the tenase complex that activates X to Xa in the cascade. By inactivating Va and VIIIa, APC disrupts these key amplification steps, dramatically reducing thrombin generation. Less thrombin also means diminished activation of inflammatory pathways, so the anti-inflammatory effect follows from this anticoagulant action. The other choices involve factors that APC does not directly inactivate; it does not target IIa (thrombin) or Xa directly, nor does it specifically inactivate VIIa or IXa.

Activated protein C exerts its anticoagulant and anti-inflammatory effects mainly by proteolytically inactivating Factor Va and Factor VIIIa. These two cofactors are essential for accelerating thrombin production: Va partners with Xa to form the prothrombinase complex that converts prothrombin to thrombin, and VIIIa partners with IXa to form the tenase complex that activates X to Xa in the cascade. By inactivating Va and VIIIa, APC disrupts these key amplification steps, dramatically reducing thrombin generation. Less thrombin also means diminished activation of inflammatory pathways, so the anti-inflammatory effect follows from this anticoagulant action. The other choices involve factors that APC does not directly inactivate; it does not target IIa (thrombin) or Xa directly, nor does it specifically inactivate VIIa or IXa.